Causes of freezing and cracking of the unit
The first thing that should be clear is what causes the unit to freeze and crack easily? There are three main reasons.
1. The unit is powered off for a long time
When the temperature is lower than -5°C, if the power outage lasts for more than 4 hours, it is likely to cause the heat exchanger to freeze and crack. In particular, when the fluorine circuit system and the water circuit system are frozen at the same time, and the compressor is restarted after the power is turned on, the compressor will directly suck the water in the external water circuit into the fluorine system, causing the entire unit to be scrapped. Therefore, when it is judged that the power outage may be prolonged for a long time, all the water in the unit, the water pump and the outdoor pipeline should be drained to prevent the unit from freezing.
2. The main board of the unit is not designed with anti-freeze protection function
When the air temperature is lower than zero °C, as long as the unit is powered on, no matter whether the unit is in working state or whether a fault code is reported, the unit will automatically supply power to the circulating pump for 10 to 15 seconds every 30 minutes, so that the hot water in the water tank is kept in the water tank and Circulate between the main engines, and use the hot water in the water tank to heat the valves, pipes, water pumps and heat exchangers of the unit to prevent freezing and cracking. However, the machine design of each manufacturer is different, and some machine mainboards do not have anti-freeze protection function. Once a fault occurs, it may cause the heat exchange sleeve to freeze and crack.
3. In summer, the water flow switch is not installed or the water flow switch is short-circuited, and the temperature measurement of the temperature probe is not accurate.
Antifreeze measures for air source heat pump in winter
As temperatures drop, securing heating has become a top priority. Whether it is an installed heat pump or a project being installed, pay attention to the winter antifreeze of the air source heat pump unit! Specifically, it can be carried out from the following aspects.
1. Strengthen the thermal insulation effect of the pipeline
It is very important to keep the pipes warm, and the exposed water pipes will cool down when the external ambient temperature decreases. Those who have not kept the pipeline warm before should put on "clothes" for the pipeline as soon as possible. After wearing clothes, the water pipe will be warm, and the temperature of the water in the pipeline will not drop too much or too quickly.
The pipe insulation of air source heat pump heating adopts B1 grade 30mm thick outdoors, and can use American B1 grade 20mm thick indoors. (Black) The outdoor thermal insulation outer layer is made of aluminum skin, and the indoor thermal insulation outer layer is bound with white cable ties. Pipeline valves and bends must be well insulated so that no exposed points of the pipeline appear.
When the heating pipeline passes through the outdoor yard pipe section of the farmer, an insulation layer needs to be installed. Before the pipeline insulation operation, the distance between the pipeline and the wall and other pipelines and equipment should be fully checked. When connecting the pipe sleeve and the pipe sleeve, the end face (circular seam) of the pipe sleeve must be coated with thermal insulation glue. The longitudinal seam of the pipe sleeve should be staggered, and the longitudinal seam should not be vertically downward. Seal the seam with glue. When the pipe sleeve is connected to the main engine and the wall, the end face of the pipe sleeve and the end face of the main engine and the wall must be coated with thermal insulation glue respectively for pressing.
2. Do not power off the unit
The air source heat pump heating of the water system uses water as an intermediate medium for heat transfer. Under normal conditions, the equipment has an anti-freeze function. When the water temperature drops to a certain temperature, the equipment will automatically start to prevent the equipment and pipelines from freezing.
If the weather temperature is relatively low, once we turn off the air energy heat pump when we go out, it may cause the water temperature in the pipeline to drop sharply. If the temperature is too low, it may freeze the equipment and cause the equipment to malfunction. Therefore, when the heat pump unit does not operate for a long time, such as: frequent power failure, shutdown of the unit at night, winter vacation, and infrequent use of the unit in winter, all the water in the unit, water pump and outdoor pipeline should be drained to prevent the unit from freezing. Bad.
3. Condensed water should be properly handled
The air source heat pump will discharge a large amount of condensed water in the process of heating. If there is a slight negligence in the discharge of the condensed water, the condensed water will be discharged through the pipes and will flow to the ground. If the temperature is below zero, the condensed water will easily freeze into ice, which may freeze the drain pipe, and then follow the drain. The pipe climbs up and eventually causes the equipment to fail to operate normally, and the condensed water should be cleaned regularly.
Therefore, the piping position of the condensed water must be properly designed. First, the installation position of the host can be raised. Under normal circumstances, the height of the host from the ground should be no less than 30 cm. For areas with severe ice and snow, it is recommended to be at least 50 cm or more. Second, add heating cables to the chassis of the host to defrost frost and ice; three , Wrap the heating cable on the outer wall of the condensate water or defrost water drainage pipe to prevent freezing.
4. Open the tee at the water inlet and outlet, and install the emptying valve
During installation, the drain valve and drain pipe should be installed at the lowest point of the water system. Even if it is not at the lowest position of the unit, the inlet and outlet of the unit should also be equipped with a drain valve. When the power outage is more than two hours or it needs to be shut down for a long time, such as when the unit is not used frequently for a long time, open the drain valve of the water inlet and outlet to drain the rainwater in the water pump of the main engine to prevent freezing and cracking after the temperature drops. cut the power. Then, perform a comprehensive inspection of the air source heat pump system before ru
nning it to ensure that there is no fault.
5. Add ethanol alcohol to the system water solution
Add more than 90% or more than 95% ethanol alcohol to increase frost resistance. The amount to be added depends on the local minimum temperature. For example, adding 1 kg of alcohol to 100 liters of water, its antifreeze index is -1°C, and the antifreeze index of adding 5 kg of alcohol is -5°C. When ethanol is added to the system for antifreeze, it should be noted that the amount should not exceed 40% of the total system water.
In addition, ethanol also has a defect, which is highly volatile. When the exhaust valve is installed in a relatively closed space, it is easy to cause the ethanol content in the space to exceed the standard. If it encounters an open flame, it may cause a fire. And because ethanol is highly volatile, it needs to be added after one or two years of use to maintain the original antifreeze performance.
6. Add antifreeze to the system
For example, antifreeze at -15°C and -25°C will increase the initial investment cost due to the high price of antifreeze. When using antifreeze, we must pay attention not to use cheap antifreeze, such as methanol-blended antifreeze, which is corrosive to pipelines and will cause great damage to valves, pipe fittings, water pumps, and unit heat exchangers.
7. Clean up debris and snow around the heat pump in time
If the ventilation of the installation location of the heat pump is not good, it will affect the heating effect of the heat pump. Therefore, it is necessary to clean it up more. It should also be noted that the fan of the main engine is blowing cold air. This will lead to insufficient heat in the air, affecting the heating effect. If the snow is too heavy, the snow must be removed in time.
